The aim of the proposed research is to improve the understanding and treatment of human anxiety. Pilot research has suggested that similar nonhuman primate behaviors are elicited by dangerous situations, by electrical stimulation of the locus coeruleus (LC) noradrenergic system, or by chemical agents which activate the LC. These behaviors were blocked by agents which diminish the activity of the locus coeruleus on its efferent projections. Agents studied with this effect included several drugs with anxiolytic action in humans. In the opposite direction, chemical agents which increase LC activity increased the same behaviors and have been reported to induce anxiety in humans. We hypothesize on the basis of these and other data that alterations in LC activity are relevant to human anxiety and to the mode of action of anxiolytic drugs. Our objective is to confirm these pilot observations in further studies of behaviors monkeys. Our methods include the use of pharmacologic agents with specific effects on LC activity, agents with known human anxiolytic activity, electrical stimulation and lesions of the locus coeruleus, and single unit activity recording from the LC in awake monkeys.